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δ ppm. Mass spectra were detected by electronic impact (EI) and obtained on an Agilent 1100 Series
VLL or JEOL the MStation JMS 700 mass Spectrometer.
3.2. Typical Procedure for the Synthesis of 4-Phenyl-2H-chromen-2-one (3a)
To a mixture of 2-hydroxybenzophenone 1a (300 mg, 1.51 mmol) and acetic anhydride (0.28 mL,
3.02 mmol) in acetonitrile (5 mL) was added DBU (0.67 mL, 4.54 mmol) and the reaction mixture was
allowed to stir for 8 h at room temperature. The solvent was removed in vacuo and the residue was
taken up with ethyl acetate (10 mL). The organic layer was washed with water, dried over anhydrous
sodium sulfate, and then concentrated to dryness. The crude was purified by column chromatography
on silica gel (hexane/EtOAc = 10/1) to afford 289 mg (86% yield) of 3a as a solid: mp 78–80 °C; Lit.
74–76 °C [16]; 1H-NMR (CDCl3, 300 MHz) δ 7.54 (m, 4H), 7.44 (m, 4H), 7.23 (m, 1H), 6.37 (s, 1H);
13C-NMR (CDCl3, 125 MHz) δ 160.7, 155.6, 154.2, 135.2, 131.9, 129.70, 128.8, 128.4, 127.0, 124.1,
118.9, 117.3, 115.1; EIMS (70 eV) m/z (rel intensity) 222 (M+, 85), 194 (95), 165 (100), 138 (30), 62 (63).
3.3. Typical Procedure for the Synthesis of 3,6-Dimethyl-4-phenyl-2H-chromen-2-one (5d)
To a solution of 4d (194 mg, 0.72 mmol) in acetonitrile (5 mL) was added DBU (216 μL, 1.446 mmol)
and the reaction mixture was allowed to stir for 20 h at room temperature. The solvent was removed in
vacuo and the residue was taken up with ethyl acetate (10 mL). The organic layer was washed with
water, dried over anhydrous sodium sulfate, and then concentrated to dryness. The crude was purified
by column chromatography on silica gel (hexane/EtOAc = 25/1) to afford 78 mg (43% yield) of 5d as
1
an oil; H-NMR (CDCl3, 300 MHz) δ 7.57–7.49 (m, 3H), 7.26–7.22 (m, 4H), 6.76 (s, 1H), 2.26
13
(s, 3H), 1.98 (s, 3H); C-NMR (CDCl3, 75 MHz) δ 162.5, 150.6, 150.5, 135.0, 133.5, 131.4, 128.8,
128.5, 128.2, 126.6, 122.7, 120.3, 116.2, 20.8, 14.7; EIMS (70 eV) m/z (rel intensity) 250 (M+, 90),
221 (52), 178 (85), 165 (30), 152 (31), 115 (61).
3.4. Typical Procedure for the Synthesis of 5,7-Dimethyl-3-phenyl-4-(4’-methylphenyl)-2H-chromen-2-
one (5m)
To a mixture of 1d (80 mg, 0.33 mmol) and phenylacetyl chloride (88 μL, 0.67 mmol) in
acetonitrile (3 mL) was added DBU (150 μL, 1.0 mmol) and the reaction mixture was allowed to stir
for 72 h at room temperature. The solvent was removed in vacuo and the residue was taken up with
ethyl acetate (10 mL). The organic layer was washed with water, dried over anhydrous sodium sulfate,
and then concentrated to dryness. The crude was purified by column chromatography on silica gel
1
(CHCl3/EtOAc = 60/1) to afford 85 mg (76% yield) of 5m as a solid: mp 200–202 °C; H-NMR
(CDCl3, 300 MHz) δ 7.18–7.11 (m, 4H), 7.03–6.99 (m, 4H), 6.91 (d, 2H, J = 8.1 Hz), 6.81 (s, 1H),
13
2.39 (s, 3H), 2.27 (s, 3H), 1.68 (s, 3H); C-NMR (CDCl3, 75 MHz) δ 161.1, 154.2, 152.7, 141.6,
137.7, 137.6, 134.9, 134.3, 130.3, 129.8, 128.6, 127.5, 127.2, 127.0, 116.3, 115.5, 23.1, 21.2; EIMS
(70 eV) m/z (rel intensity) 340 (M+, 95), 325 (38), 312 (100), 297 (17), 252 (11), 189 (10), 126 (9),
105 (12).